According to the American Lung Association, each year over 344,000 Americans die of lung disease, making it the third most frequent cause of death in this country. An even more staggering statistic is that an additional 35 million Americans are living with chronic, debilitating lung diseases. Not uncommonly, patients with lung disease or at risk for lung disease undergo various forms of thoracic imaging. This has led to an unprecedented number of patients presenting to lung specialists with nodular abnormalities suspicious for cancer or interstitial abnormalities suspicious for various forms of Interstitial Lung Disease (ILD). When a patient is found with these abnormalities, it is often necessary to biopsy the tissue to establish the diagnosis, the prognosis, and guide further therapy.
One of the factors that contribute to lung disease is smoking. According to the Center for Disease Control, there are 94 million past and current smokers in the US. Half are over the age of 45 (the age at which lung cancer incidences increase). Many smokers are concerned about the risk of developing lung cancer, which explains the growing success of CT based lung cancer screening programs. The problem with these programs is that about 30% of the screened patients will have suspicious nodules suggestive of cancer, but only a small percentage are ultimately proven to be cancer. While there is considerable evidence to suggest that CT based lung cancer early detection programs are beneficial in detecting early stage lung cancer, the area of biggest clinical unmet need is in the ability to differentiate between a benign and malignant nodule. The currently available lung biopsy techniques, such as CT guided biopsy, bronchoscopy, thoracoscopy or thoracotomy are either too insensitive or too invasive, limiting their usefulness and making the determination difficult at best. Thus one of the most significantly limiting factors that has prevented success of lung cancer screening programs has been a lack of safe and effective ways to sample lung tissue in a minimally invasive fashion.
A similar dilemma exists for the diagnosis of interstitial lung disease. In a number of cases where there is a suspicious imaging pattern suggestive of ILD or cancer, it is desirable to sample the tissue so that a pathologist can establish the exact cause of the abnormality. The problem is that the current lung biopsy techniques are invasive, painful and many require general anesthesia, which is not always well tolerated in patients with impaired lung function. Many patients are judged “not a surgical candidate,” due to the patient's degree of medical disability and lung dysfunction. Both thoracotomy (a large incision through the chest muscles and between the ribs) and thoracoscopy (the use of a scope and other working ports through the ribs to operate in the space around the lung) can be very disabling and painful. In fact, these forms of surgery are generally much more painful and disabling than other forms of surgery, such as heart surgery and abdominal surgery due to the manipulation of the chest wall muscles, ribs and intercostal nerves between the ribs. Currently, thoracotomy and thoracoscopy often require long hospital stays and even longer recovery times. Both procedures can lead to chronic pain syndromes in a surprisingly high percentage of patients.
When a determination is made to biopsy a lung nodule 510, there are several options, as illustrated in FIG. 1. One option is to use a bronchoscopic approach. This, however, is most useful for larger, more central tumors. Generally, a central approach is not a useful option for the more common small nodules since most lung nodules 510 are in the periphery 501 of the lung 502 and not connected to the airway 503. Another option is to use a CT guided needle biopsy 522 of the lung 502. While this approach can be useful in larger, more peripheral tumors, it is not particularly helpful for smaller nodules 510 that are deeper in the lung 502. Furthermore, only a small core sampling of the tissue can be taken, and thus false negative biopsies are common. Additionally, since there is no mechanism to seal the lung 502, bleeding complications and pneumothorax are frequent concerns, occurring in nearly 20% of patients.
Thoracic surgical approaches to biopsy lung nodules can be divided into two categories: thoracotomy and thoracoscopy. A thoracotomy 530 is a 300 to 450 mm (12 to 18 inches) incision 532 on the chest wall skin 304, followed by division or dissection of the major back muscles to move them out of the way, partial removal of the rib 42, and the placement of a rib spreader 534 to provide intra thoracic access to the operating surgeon. The advantage of a thoracotomy is that the surgeon has excellent access to the intrathoracic structures, and can see and manually feel the lung 502 and other structures directly. This is especially important when targeting a tiny lung nodule 510. The major disadvantage is the degree of pain and the potential for complications related to the magnitude of the incision. A thoracotomy is well known to be a very painful operation for the patient, with significant acute and chronic pain issues. Because of the degree of invasiveness, it is reserved only for the most optimal surgical candidates as many patients with significant lung disease cannot tolerate a thoracotomy and recover without significant morbidity and mortality. For these reasons it is recognized that there is a need in the art to lessen the invasiveness of thoracic surgery.
One approach that has been around for many years is to utilize an endoscope 542 to facilitate visualization within in the chest, thereby precluding the need for a large thoracotomy incision. Thoracoscopy 540 is the use of a specialized viewing instrument, usually a rigid endoscope 542, introduced through a thoracostomy, or a small hole placed in between the ribs 42. Once the endoscope 542 is placed in the space that surrounds the lung 502, known as the pleural space, usually two to three additional thoracostomy holes are made to introduce additional instruments 544. Additional instruments 544 include grasping instruments, cutting instruments, and in the case of a thoracoscopic lung biopsy, a cutting stapler, such as the Ethicon Endosurgery Endo GIA 45 mm stapler. Using the endoscope 542 and the other instruments 544, a “triangulation” technique is utilized where, for example, the endoscope 542 is used to view as the grasping instrument is brought in from one direction, and the stapler is brought in from another, and tissue is cut with the stapler and removed through one of the ports.
One of the major disadvantages of this approach is the number and size of ports needed to triangulate in order to carry out the biopsy. While this approach is commonplace in most laparoscopic operations carried out in the abdomen, such as the laparoscopic cholecycstecomy, there are unique features of an endothoracic operation that make this approach undesirable. First, it is almost always necessary to utilize a general anesthetic to perform a thoracoscopic lung biopsy. In addition, it is nearly always necessary to utilize a specially placed, and more complicated dual lumen endrotracheal tube so that artificial ventilation can be delivered to the opposite lung, and excluded to the side of the lung that is being biopsied. This technique, known as single lung ventilation, is needed for nearly all current thoracoscopic operations. Many patients with end stage lung disease, however, are unable to tolerate a general anesthetic, and of those that tolerate a general anesthetic, many cannot tolerate single lung ventilation because their respiratory reserve is so limited. Additionally, the intercostal spaces are particularly sensitive to pressure, as there is a fixed and limited space between the ribs, and the intercostal nerve runs underneath each rib in the intercostal space. Each time a thoracostomy is performed, pain can be severe and prolonged. This is especially the case with larger thoracostomy port sizes, such as 10 mm and 12 mm ports that are commonly used for contemporary thoracoscopy. Some studies have estimated that as many as one third of patients have chronic pain in their chest wall up to one year after thoracoscopy, and it is believed this is due to intercostal nerve irritation that occurs when multiple, large ports are introduced into the pleural space between the ribs. Single port procedures have been reported in the literature for very limited procedures, but they generally require very large incisions, 30 mm or more, to get multiple instruments through a single port.
Because of the drawbacks of bronchoscopy, open lung biopsy, and thoracoscopy, a large percentage of patients are simply not referred for lung biopsy because the referring physician is uncomfortable with the degree of invasiveness coupled with the accuracy of the available techniques. Given the advancements in imaging and the improved appreciation of the value of tissue diagnosis in lung disease, new techniques are needed to biopsy the lung in a precise, minimally invasive manner.